Cam shaft manufacturers have been making cam shafts by one of various techniques generally involving the steps of placing a number of cam lobes in predetermined positions along a cam shaft, expanding the cam shaft radially outwardly to engage the lobes and thereby locking the lobes in the predetermined positions along the shaft. One technique recently discovered and taught in U.S. Pat. No. 5,220,727 to Hochstein involves placing a propellant in the cam shaft and deflagrating the propellant in order to expand the cam shaft radially into engagement with the cam lobes. The subject invention is essentially an improvement on this promising technique.